Generally, an air purifier may be an ozonolysis material coated on a radiator, in order to change ozone of the atmosphere into oxygen. In addition, an air purifying system includes the air purifier and an on-board diagnosis (OBD) sensor, and determines whether the air purifier is operating normally.
Presently, there are direct type OBD sensors and indirect type OBD sensors. First, the direct type OBD sensor is an ozone sensor for directly detecting an ozone density of the radiator. The ozone sensor must have good precision in order to detect the ozone density (0˜200 ppb) in the atmosphere, and durability in order to interrupt a failure generated by a foreign substance of the atmosphere. Particularly, the ozone sensor must have a high precision in order to detect the ozone density lower than 200 ppb.
However, since the ozone sensor must have a high precision, such sensors are expensive. In addition, the ozone sensor must maintain a fixed moisture, temperature, etc., because the ozone sensor is affected by moisture, temperature, etc. However, since the ozone sensor must be provided with many elements in order to maintain a fixed moisture, temperature, etc., the sensor is even more expensive.
On the other hand, the indirect type OBD sensor detects an electrical resistance of the ozonolysis material, and detects a coated thickness of the ozonolysis material through the detected electrical resistance. A method for detecting the electrical resistance uses a printed circuit board (PCB) on which the ozonolysis material is coated. That is, the method detects an electrical resistance of the ozonolysis material by supplying an electric current to the PCB. However, since an adhesion between the radiator (aluminum ware) and the ozonolysis material is different from an adhesion between the PCB (epoxy ware) and the ozonolysis material, a problem occurs in that there is a difference between a coated thickness on the PCB and a coated thickness on the radiator.
The information disclosed in this Background of the Invention section is only for enhancement of understanding of the background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art that is already known in this country to a person of ordinary skill in the art.